The proposed algorithm is validated with different data lengths, ranging from 1 to 360 days. Fig. REF  illustrates the error rates of the 123-bus system, with and without DER, over different lengths of the PG&E data set. With 20 days' measurements (\(24\times 20 = 480\)  data points), the proposed method can achieve zero error. This result is better than the single-phase system presented in [1]}, which requires 30 days' observations. The reason is that at time \(n\) , our proposed algorithm uses measurements from three phases, which contain more information than the single-phase system. The frequency of distribution grid reconfiguration ranges from hours to weeks [2]}, [3]}. Section REF  demonstrates that the topology can still be estimated by increasing the sampling frequency of smart meters.
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